refactor: Use early-return in extract_people_from_message().

frontend_tests/node_tests/people.js

@@ -431,6 +431,12 @@ initialize();
 initialize();
 
 (function test_extract_people_from_message() {
+    var unknown_user = {
+        email: 'unknown@example.com',
+        user_id: 500,
+        unknown_local_echo_user: true,
+    };
+
     var maria = {
         email: 'athens@example.com',
         user_id: 452,
@@ -446,6 +452,13 @@ initialize();
     assert(!people.is_known_user_id(maria.user_id));
     people.extract_people_from_message(message);
     assert(people.is_known_user_id(maria.user_id));
+
+    // Get line coverage
+    message = {
+        type: 'private',
+        display_recipient: [unknown_user],
+    };
+    people.extract_people_from_message(message);
 }());
 
 initialize();

static/js/people.js

@@ -744,20 +744,23 @@ exports.extract_people_from_message = function (message) {
 
     // Add new people involved in this message to the people list
     _.each(involved_people, function (person) {
-        if (!person.unknown_local_echo_user) {
-
-            var user_id = person.user_id || person.id;
-
-            if (!people_by_user_id_dict.has(user_id)) {
-                exports.add({
-                    email: person.email,
-                    user_id: user_id,
-                    full_name: person.full_name,
-                    is_admin: person.is_realm_admin || false,
-                    is_bot: person.is_bot || false,
-                });
-            }
+        if (person.unknown_local_echo_user) {
+            return;
         }
+
+        var user_id = person.user_id || person.id;
+
+        if (people_by_user_id_dict.has(user_id)) {
+            return;
+        }
+
+        exports.add({
+            email: person.email,
+            user_id: user_id,
+            full_name: person.full_name,
+            is_admin: person.is_realm_admin || false,
+            is_bot: person.is_bot || false,
+        });
     });
 };